View Full Version : Why is solar power still so expensive?
03-07-2004, 11:25 AM
I've heard it said that cheap solar collectors aren't efficient, and efficient solar collectors aren't cheap. Apparently, regardless of whether you buy a cheap-and-inefficient solar collector, or an expensive-and-efficient solar collector, in either case, it'll take nearly the entire 30-odd year useful lifetime of the collector to generate enough electric energy to pay for itself.
So, firstly, why does existing solar panel technology cost so much per square centimeter? And secondly, what happened to all those promising "cheap and efficient solar power" technologies (like those sandwiched plastic layer thingies) that were all just "about to happen"?
03-07-2004, 02:48 PM
The newer technologies are being developed and continue to work better and better (higher efficiency). However, a couple of real limitations will continue to exist. First, you are looking for a material which will take radiant energy and directly convert it to electric current. This is no small trick so making the materials to do this will likely always be a relatively expensive process.
Second, you have to design the material to be efficient with full sunlight at noon in the middle of the summer and also at 4 PM on a winter afternoon. The fact of the matter is that any solar device is only going to average (year round) about 10 or 15% of peak power output (which might mean only 3 to 5% actual efficiency). Then you have to compare the costs with systems that can run around the clock at 100% power level.
The good news is that solar will be eventually become economic. The bad news is that it will probably be because everything else gets so expensive.
03-07-2004, 03:01 PM
Don't forget the "economy of scale" effect too. Solar power is still relatively unusual, so we don't get the economies that come from mass production, competition, market forces and so on. Even thought the scientific principles are well understood, it hasn't yet become mainstream enough for the economics to settle down.
03-07-2004, 03:33 PM
There can also be diseconomies of scale and I recently read somewhere the claim (which I cannot attest) that solar panels are currently being made from discarded silicon chips and that they would considerably more expensive if made in large quantities.
Leaving that point aside, thermal generators have been under intensive development for, what, 120 years, while solar panels are just much more recent. I suspect that solar power will never be that much cheaper, but when we get serious about CO2 emission control, the costof thermal power will get a lot more expensive and then solar (and wind) power will be competitive.
03-07-2004, 07:00 PM
First, you are looking for a material which will take radiant energy and directly convert it to electric current. This is no small trick so making the materials to do this will likely always be a relatively expensive process.
So ... what kinds of expensive tricks are necessary to create such devices? What drives the cost per square centimeter?
03-08-2004, 11:00 PM
Most solar cells are basically silicon crystals but they are "doped" with various impurities which allow a electrical potential to develop which is released by incidence of light. Silican cells are usually about 10% efficient but could be as high as 20%. The theoretical maximum efficiency of a single layer cell is about 30% and almost 25% has been reached with gallium arsenide. However, to go higher, you need multi-layer cells which are currently a major challenge to make at all, let alone cheaply.
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